Total internal reflection lens to improve color mixing of an led light source

ABSTRACT

A multi-color LED illumination device and specifically a lens comprising a cylindrical opening extending into the lens from a light entry region at which one or more LEDs are configured. A concave spherical surface extends across the entirety of the light exit region of the lens, and a TIR outer surface shaped as a CPC extends between the light entry region and the light exit region. There are various diffusion surfaces placed on the sidewall surface of the cylindrical opening, as well as its upper planar surface and the exit surface of the lens. Lunes can also be configured on the sidewall surfaces of the cylindrical opening. The combination of lunes, diffusion elements, and the overall configuration of the lens provides improved color mixing and output brightness using three interactions in a first portion of light and two interactions in a second portion of light. Those interactions includes two refractions either with an intermediate reflection or not, all of which are necessary to achieve the improved performance of the multi-color LED illumination device and lens hereof.

BACKGROUND OF THE INVENTION CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application No.17/386,486, filed Jul. 27, 2021; which is a divisional application ofU.S. Pat. Application No: 15/000,469, filed Jan. 19, 2016, now U.S. Pat.No. 11,106,025, issued Aug. 31, 2021; all of which are incorporated byreference as if reproduced in their entirety herein.

FIELD OF THE INVENTION

This invention relates to a light emitting diode (LED) illuminationdevice, and more particularly to a total internal reflection (TIR) lenswith an outer compound parabolic concentrator (CPC) surface to moreefficiently mix LED output in a relatively small parabolic aluminumreflector (PAR) configuration.

DESCRIPTION OF THE RELEVANT ART

In the field of optics, and specifically non-imaging optics, there aregenerally two types of optic devices that transfer light radiationbetween a source and a target. A first type of optic device isoftentimes referred to as an illuminator; the second type of opticdevice is generally referred to as a concentrator. In an illuminator,the target is generally outside the illumination device to illuminate anobject using a variety of light sources generally inside theillumination device. A popular light source can be a solid state lightsource, such as a light emitting diode (LED). Conversely, a concentratoris generally used to concentrate a light source outside of theconcentrator onto a target inside the concentrator. A popular form ofconcentrator is a solar concentrator, used to concentrate solar energyfor photovoltaics.

Two popular forms of a concentrator are either a compound ellipticalconcentrator (CEC) or a compound parabolic concentrator (CPC). Eitherform concentrates energy from typically an infinite distance away ontoreflective surfaces of the CEC or CPC, and then to a focal point nearthe base of the CEC or CPC. Generally, a CPC is beneficial over mostother types of concentrators, including the CEC or the generalizedparabolic concentrator, in that a CPC can accept a greater amount oflight and need not accept rays of light that are solely perpendicular tothe entrance aperture of the concentrator.

FIGS. 1-3 illustrate differences between a CPC and a parabolicconcentrator in general, as well as the operation of a CPC in receivingrays of light over a fairly large acceptance angle φ Referring to FIG. 1, CPC 10 is formed from two parabolic mirrors. One arm 12 of CPC 10 isformed by cutting a parabola at point 16 and discarding the portion ofthe parabola shown in dashed line. The other arm 14 of CPC 10 is formedby cutting the parabola at point 18 and discarding the portion of theparabola shown in dashed line. The arms 12 and 14 are formed equaldistance from central axis 20, and rotated about central axis 20 to formthe symmetrical CPC reflective surface.

Turning to FIG. 2 , shown in cross section is a general parabolicconcentrator 26 with reflective surface 22 rotated about central axis24. Comparing FIGS. 1-2 , the entrance aperture of parabolicconcentrator 26 is much larger than that of CPC 10. However, as shown inFIG. 3 , CPC 10 can receive light 28 at an acceptance angle φ dissimilarfrom light that is perpendicular to the entrance aperture. Accordingly,CPC 10 accepts a greater amount of light than other forms ofconcentrators, such as the parabolic concentrator.

Contrary to concentrators, illuminators send light outward as opposed toreceiving light inward. Illuminators typically have a light sourceplaced near the base of a secondary optical element. The light sourceforms a primary optical element in that it generates light, examples ofwhich include incandescent lights or solid state lights, such as lightemitting diodes (LEDs). LEDs are solid state devices that convertelectrical energy to light, and generally comprise one or more activeregions of semiconductor material interposed between oppositely dopedsemiconductor layers. Light is emitted from the active region andsurfaces of the LED.

In order to generate a desired output color, it is sometimes necessaryto mix colors of light using what is known as multi-color LED lights.Multi-color LED light can include one or more LEDs, which are mounted ona substrate and covered by a hemispherical silicon dome in aconventional package. The LEDs can emit blue, red, green, or othercolors, and a combination of such can be mixed to produce any desiredcolor spectrum.

Because of the physical arrangement of the various LED sources, shadowswith color separation and poor color uniformity can exist at the output.For example, a source featuring blue and yellow may appear to have ablue tint when viewed head on, and a yellow tint when viewed from theside. Thus, one challenge associated with multi-color light LEDs ishaving good spatial and angular separation, otherwise known as spatialand angular uniformity projected outward in the near and far field ofthe LED source.

One method used to improve spatial and angular uniformity, and thuscolor mixing, is to reflect or refract light off several surfaces beforeit is emitted. Color mixing can also be achieved using a combination ofreflection and refraction. Both have the effect of disassociating theemitted light from its initial emission angle. Uniformity typicallyimproves, but each light interaction (reflection and refraction) has anassociated loss.

FIG. 4 illustrates secondary optical elements used in conjunction withthe primary optical element (LED source). The secondary optical elementsof FIG. 4 solely reflect light using either lens 30 or reflectivehousing 32. Both the reflective housing 32 and lens 30 are usedprimarily to collimate the light output, as shown by the collimatedoutput of rays 40 and 42. The LEDs, e.g., red, green, blue, and white,can be spaced from each other along a base plane to form array 34further shown in FIG. 5 . The array of LEDs extends in planar fashionalong a base plane with cover 36 covering the planar arrangement ofLEDs. Cover 36 may be mounted to the base, which is preferably a printedcircuit board with a heat sink. LED array 34 is centered andperpendicular to central axis 38, which is preferably the central axisfor reflector housing 32 and lens 30 being symmetrical about axis 38.

As shown in FIG. 4 , lens 30 is a transparent lens made of plastic orglass, having a refractive index greater than air. As light beam 40enters lens 30, it enters at a right angle to the convex sphericalsurface and reflects from the outer surface in collimated fashionoutside of the lens. Thus, lens 30 is typically known as a total innerreflection (TIR) lens, with the angular outside surfaces made of areflective material in the shape of a parabola rotated around centralaxis 38. The reflective portion is mathematically described as aparabola f(y) = ay² + by + c, where y is the height of the lens from anentry to an exit.

Rays which do not enter the concave entry of lens 30 can be reflectedfrom housing 32, such as ray 42. In either instance, FIG. 4 illustratesone example of total internal reflection using two reflective surfaces,one on the external surface of lens 30 and the other on the externalsurface of housing 32. In either instance, only a single lightinteraction occurs, that being a reflection rather than refraction.Thus, no matter where LEDs 41 appear within, for example, a matrix withdifferent colors of LEDs spatially positioned across the matrix, theoutput of the secondary optical element is collimated using a singlelight interaction.

Turning now to FIG. 6 , lens 44 is shown. Lens 44 does not require areflective housing or an air gap between a reflective housing and a TIRlens. Lens 44 is placed in close proximity to the LED array 34 so as tocapture all light emitted from the LEDs, without need of a reflectivehousing. Lens 44 includes a spherical, concave entry surface 46 and aspherical, convex exit surface 48. In addition, exit portion 50 can bemade neither convex nor concave. The term convex is used to describe thespherical portions with convex being relative to the lens inner regionand extending inward toward a center of the lens, while concave extendsoutward from the lens inner portion. Both the inward and outwardextensions occur symmetrically about a central axis.

As shown in FIG. 6 , any rays which extend from LED array 34 are eitherreflected 52 or refracted 54. Ray 52 reflects from the TIR outer surfaceof lens 44, whereas ray 54 refracts from convex surface 48. According tothe law of refraction, n_(p) sine φ_(p) = n_(a) sine φ_(a). For example,using this equation and knowing that the index of refraction for air,n_(a), is less than the index of refraction for plastic, n_(p), thenφ_(p) < φ_(a). This angular relationship is described in the anglesφ_(p) and φ_(a) shown in FIG. 6 to indicate the refraction and thechange in angle from the perpendicular as ray 54 extends from, forexample, plastic lens to air. In either case in which ray 52 isreflected or ray 54 is refracted, only one light interaction is neededfor lens 44. Moreover, only one light interaction is needed to form acollimated output; thus, a collimation lens. It is noted that concavesurface 46 is arranged so that whatever rays emit from LED array 34,those rays enter the concave surface 46 at substantially right angles;thus, no refraction takes place on the light entry region.

FIG. 7 illustrates lens 60 having a TIR surface symmetrical around acentral axis. However, instead of the light entry region being concave,the light entry region 62 of lens 60 is convex. Moreover, there arestraight sidewall surfaces 64 of equal distance from the central axis,extending from the planar base on which LED array 34 is attached toconvex surface 62. Thus, rays 66 are refracted on convex surface 62,whereas rays 68 are refracted on the sidewall surface 64 and thenreflected on the TIR surface. No more than one refraction occurs ineither instance.

In addition to convex light entry surface 62, light exit surface 70 canalso be convex as shown in dashed lines. Unfortunately, using a convexentry and exit surfaces causes light rays 72 to undergo two refractions,one on the entry and another on the exit. The second refraction at theexit may retain collimation, however, angular uniformity becomes aproblem as the output projects at intensity peaks that are spaced fromone another, and not evenly mixed across a plane perpendicular to thecentral axis. Moreover, two light interactions, both of which arerefractive, significantly impacts on the output color spectrum as wellas the output brightness itself. It is typically important to avoidrefraction, since refraction can change the propagation path of theemitted light depending on the light wavelength. For example, arefracted beam that is blue at the source can take on a differentpropagation path through the lens than a light beam that is green. Thus,in settings that utilize, for example, red, green, blue, and white LEDsources, it is generally desirable to avoid refraction, since refractionis typically wavelength dependent. It is also advantageous to avoidnumerous light interactions, including both refraction and reflection.The more light interactions that occur, the output lumen brightness candeleteriously be affected.

In each of the lens structures described hereinabove, collimation isachieved at the projected output. However, pure collimation containscertain drawbacks. For example, the collimated output using two lightinteractions at shown in FIG. 7 has an inherent color mixing drawback.The output, while having intensity peaks, also has relatively poorangular uniformity. Each LED within the module 34 produces an outputthat extends outward in a radial angle approximately 180 degrees. Forexample, a red LED can be spaced from a green LED, and the output ofeach project their angular output a spaced distance from one anotheronto the two-light interactive lens which then, through refractionand/or reflection, collimates and projects the nonuniform angularoutput. The poor angular uniformity of the output will, unfortunately,negatively impact on color mixing. If improved color mixing is desired,pure collimation should not be the primary reason for selecting a lens.Moreover, color mixing can oftentimes reduce the output intensity andtherefore having more than two light interactions is problematic if lowpower LED applications are all that are possible.

It would be desirable to achieve an improved lens design that hasimproved color mixing while selectively using a modified collimatedoutput from certain portions of the lens design. Such a lens may requiremore than two light interactions to achieve not only better angularuniformity, and thus color mixing, but also can be implemented if theLED output can be appropriately increased. By using an increased LEDoutput with at least three light interactions, it is further desirableto collimate the outer radial regions of the lens output while avoidingcollimation on the inner radial regions of the lens output. Selectivelytailoring collimation to the outer region affords more control throughappropriately placed diffusion lunes that diffuse the rays fromcollimated from the outer region to not only improve angular uniformitynot available in conventional lens designs but also to maintain improvedcolor mixing across the entire output surface of the lens consistentwith what is achieved in the inner radial region.

Improved color mixing across the entire output surface is achieved notthrough collimation lenses as shown in FIGS. 4, 6 and 7 , or derivativesthereof, since such lenses do not selectively control the lens output atthe outer radial region, nor do they remove the concave or convex entryor exit surfaces at the inner radial region that cause poor angularuniformity, and thus poor color mixing of an LED output.

SUMMARY OF THE INVENTION

The problems outlined above are in large part solved by an improved lenshaving a straight entry at the inner radial region to improve colormixing of LED output near a central axis and at the detriment ofcollimation from that inner radial region. The improved lens also has astraight sidewall entry at the outer radial region to improve colormixing of LED output farther from the central axis even though such LEDoutput is collimated. The straight sidewall entry is, however,configured with a surface that diffuses or scatters the light from theLED as it impinges upon a CPC reflective output surface and then to aconcave spherical exit bounded by the CPC reflective outer surface. Byconfiguring the non-collimated light exiting the inner radial region andthe collimated, yet diffusion treated, light exiting the outer radialregion, the outer radially emitted light surrounds the inner radiallyemitted light to make the projected light appear in the near and farfield to be better color mixed across a broader angular range of the LEDoutput. The lens, used as a secondary optical element, thereforeachieves an improved methodology for transferring color mixed light fromone or more LEDs.

According to a first embodiment, a lens is provided for receiving lightfrom an LED. The lens includes a cylindrical opening extending into thelens from a light entry region. The cylindrical opening is configured toreceive the entirety of light from the LED. Across the entirety of alight exit region is a concave spherical surface. The concave sphericalsurface extends inward towards a central axis and is symmetric aboutthat central axis. The arcuate path of the concave spherical surfaceextends to the entire outer surface near the light exit region. Theouter surface is a TIR outer surface shaped as a CPC, which extendsbetween the light entry region and the light exit region.

The cylindrical opening comprises a sidewall surface facing toward andequal distance from a central axis. The sidewall surface receives lightat the outer radial region, where light exits the LEDs more than, forexample, 20 degrees from a central axis and which do not strike thestraight, upper substantially circular plane that is perpendicular tothe sidewall surface and forms the upper region of the cylindricalopening. Any light that strikes the upper substantially circular planeis referred to as the light at the inner radial region.

The sidewall surface preferably comprises a plurality of lunes, each ofwhich is substantially planar having a length and width, the lengthbeing greater than the width and extending parallel to the central axis.The lunes are spaced equal distance from the central axis and terminateon the upper region of the cylindrical opening. Depending on the numberof lunes, the upper plane becomes more circular as the number of lunesincreases. The number of lunes is preferably between 8 and 20. If morethan 20 lunes are used, for a given lens dimension, more collimation canoccur for radially extending LED light output, which is deleterious tothe desired color mixing in the inner radial region of the lens. Lessthan 8 lunes would form more of a square upper plane causing a greaterbeam intensity loss than what can be achieved by simply increasing theLED output.

The lens comprises a unibody construction and is of the same materialcontiguous throughout, with no seams, adjointments, or abutments of onebody to another within the entirety of the lens, so that the lens isseamless and preferably made from, for example, a molding apparatus. Theunibody material preferably has a refractive index greater than air, andis configured between surfaces formed by the sidewalls of thecylindrical opening, the concave spherical surface extending across theentirety of the light exit region, and the TIR outer surface shaped as aCPC.

According to another embodiment, an illumination device is provided. Theillumination device comprises a unibody lens having a reflective outersurface shaped as a CPC around a central axis between an entry surfaceand a spherical concave exit surface. A plurality of LEDs are configuredproximate to the entry surface and spaced from each other along a baseplane perpendicular to the central axis. A plurality of lunes extendsperpendicular from the base plane, each of the lunes having an elongatedplanar surface, wherein the elongated planar surface is configured anequal distance along the central axis to an upper plane that is parallelto the base plane. The upper plan extends radially outward from thecentral axis to a distal radius. Each of the plurality of lunesterminates at a 90° angle on the distal radius to form a cylindricalsurface bound by the plurality of lunes, and the upper plane facinginward toward the base plane and the LEDs.

The filling material of the unibody lens can be plastic or glass, forexample. Such filling material can be injection molded acrylic,polymethylmethacrylate (PMMA), or any other form of transparentmaterial. The reflective surface of the outer TIR surface shaped as aCPC comprises any surface which reflects the light rays coming from theinternal fill material, such as a square plate polyhedral reflectivesurface.

According to all embodiments, the lens hereof purposely avoids using anyhousing reflector, but is implemented in a PAR form factor that providesuniform color throughout the standard 0°, 25°, and upwards to 40° beamangles. The lens preferably has a pipe from the entry portion to theexit portion of no more than 1.4 inches, with the spherical concave exitsurface extending to the TIR reflector surfaces being no more than 2.5inches. The bottom diameter of the lens at the base plane is no morethan 1 inch. Accordingly, the present lens is compact; thus,illustrating one benefit of using a CPC dimension rather than a standardparabolic dimension. The relatively small form factor that utilizes acompact design implemented through a CPC configuration achieves not onlysuperior color mixing with improved, if not superior, brightnesscontrol, but does so using the unique lens configuration on both theentry and exit surfaces, and further being able to adjust the drivecurrent supplied to the LED loads to accommodate any changes inwavelength-dependent refraction.

A methodology is provided to achieve these beneficial results oftransferring light from an LED. The method includes transmitting a firstportion of the light through air at a plurality of first angles relativeto a central axis around which the lens is formed. Accordingly, thefirst portion of light, as well as a second portion of light,transmitted from the light source is typically Lanbertian, which meansthat the LED matrix or array of spaced LEDs emits light in alldirections. However, the TIR secondary optical element extracts andcollimates the light at the light exit surface. The method furthercomprises first refracting the first portion at a sidewall surface ofthe light entry surface. The refracted first portion of light is thenreflected from an outer surface of the lens back into the lens, where asecond refracting takes place. The second refracting refracts thereflected first portion from a spherical concave surface into the air.

According to a further embodiment, the method comprises transmitting asecond portion of light through air at a plurality of second anglesrelative to the central axis less than the plurality of first angles. Athird refraction occurs whereby the second portion is again refracted ata planar surface perpendicular to the central axis into the lens. Afourth refraction occurs whereby the third refracted second portion isagain refracted from the spherical concave surface into the air.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to theaccompanying drawings.

FIG. 1 is a plan view of a compound parabolic shape relative to aparabolic shape;

FIG. 2 is a plan view of a parabolic shape having a wider radius from acentral axis than the compound parabolic shape;

FIG. 3 is a plan view of a compound parabolic concentrator typicallyused to accept and concentrate solar rays onto a focal point;

FIG. 4 is a side cross sectional view of a lens mounted within areflective housing to achieve total internal reflection;

FIG. 5 is a view along plane 5 of FIG. 4 showing an array of LEDs;

FIG. 6 is a side cross sectional view of a TIR lens absent a reflectivehousing to achieve total internal reflection using only one lightinteraction;

FIG. 7 is a side cross sectional view of a TIR lens absent a reflectivehousing to achieve total internal reflecting using no more than twolight interactions;

FIG. 8A is a side cross sectional view a lens with a TIR outer surfaceshaped as a CPC and having up to three light interactions to achieveimproved output collimation and color mixing according to one embodimentof the present invention;

FIG. 8B is a blow up cross sectional view of the diffusion surfaces;

FIG. 9A is a view along plane 9 of FIG. 9 showing a cylindrical openinghaving a plurality of lunes arranged along the sidewall surface of thecylindrical opening; and

FIG. 9B is a blow up cross sectional view of the two lunes of a TIR lensshaped with a CPC.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 8A illustrates lens 80 filled with material 82, e.g., an injectionmolded light transparent material. Material 82 is bound between lightentry region 84, light exit region 86, and TIR outer surface 88, whichis shaped as a CPC. TIR outer surface 88 has a smaller exit region thena parabolic TIR, shown in dashed line 90. Moreover, exit region 86comprises concave spherical surface 94, instead of most conventionalparabolic lenses having a flat surface, shown in dashed line 96. Thus,FIG. 8A illustrates a comparison between a conventional parabolic lens91 and the present lens 80. Present lens 80 is not only shaped as a CPC,but also is more compact in its configuration, being less than 2.5inches in diameter for exit region 86, 1 inch in diameter for entryregion 84, and no more than 1.4 inches in height from the entry regionto the exit region. The entry region is defined as a planar base onwhich the LEDs 100 reside. The overall maximum height of the compact PARdimension of the present invention is 1.4 inches from the planar base tothe outer extents of the TIR reflective surface 88 at which it joins theconcave spherical surface 94.

Of import, the compact PAR configuration of lens 80, which is shaped asa CPC, is beneficial over the conventional parabolic lens. Conventionallens 91 can receive light passing through a sidewall surface 102 nearthe light entry region 84, such sidewall surface constitutes thesidewall surface of a cylindrical opening, also having an upper planarsurface 104. The dashed line indicates refraction at angles φ_(PA1) andφ_(PM2) at the plastic-to-air interface of the parabolic lens. Next, areflection occurs at the TIR external surface of lens 91, shown atangles φ_(R3) and φ_(R4), whereby the reflected light is then refractedat the exit surface of lens 91 by the interaction of φ_(PM2) to φ_(PA2).The resulting exiting light ray or beam may not be collimated. Thus, itis desirable to form a collimated lens, which can be achieved by strictadherence to the configuration of lens 80, with a cylindrical openingthat forms sidewall surface 102 and upper planar surface 104, along withconcave spherical surface 94, where surface 94 must extend across theentirety of the light exit region from the central axis about which lens80 is symmetrical to external surface 88.

FIG. 8A illustrates that any beam that strikes sidewall surface 102 mustgo through three light interactions. For example, beam 106 goes througha refraction φ_(A1)/φ_(M1) at sidewall surface 102 to a reflectionφ_(R1)/φ_(R2), to another refraction φ_(M2)/φ_(A2) on surface 94. Beam108 also goes through three interactions. The first interaction is arefraction, followed by a reflection, ending with another refraction.Thus, every beam that enters the sidewall surface near the beam entryportion goes through the sequence of refraction, reflection, andrefraction, finally exiting the light exit region as a collimated lightbeam, which is not achievable in conventional lens 91. For brevity andclarity of the drawings in showing the various ray paths, which canexceed several hundred if not thousands, only two are shown for lens 80entering the sidewall surfaces. Moreover, so as not to obscure the raypath line, material 82 is not shown in cross-hatch; however, it isunderstood that in the region between the cylindrical opening near thelight entry region to the concave spherical surface of the light exitregion, lens 80 is filled with unibody material 82, which is contiguousand non-interrupted, such as injection molding.

In addition to transmitting a first portion of light from LEDs 100through air attributable to the cylindrical opening where it impingesupon sidewall surface 102, a second portion of light can be sent throughair of the cylindrical opening where it impinges upon planar uppersurface 104. The first portion of light is first refracted at surface102, then reflected at surface 88, then second refracted at surface 94.The second portion of light 110 is third refracted φ_(A3)/φ_(M3), if itimpinges upon the planar upper surface at a non-perpendicular angle,where it is later fourth refracted φ_(M4)/φ_(A4) on surface 94.

The first portion of light from the outer radial region of the LEDoutput is shown collimated as it exists as beam 106. The first portion,however, passes through diffusion surfaces on the sidewall surface 102to scatter, or mix the light output to achieve both angular and linearuniformity of the output. Such diffused, collimated output is purposelyplaced on the outer radial region to surround the non-collimated innerradial region of the LED output to achieve color mixing at the near andfar field. The improved color mixing is due to the unique configurationof the cylindrical opening of the light entry region to the concavespherical surface of the light exit region, bound by a reflective outersurface being CPC-shaped to achieve an overall compact dimension of aPAR lamp.

On sidewall surface 102, planar upper surface 104, and exit surface 94of lens 80 is a diffuser surface 112, shown in FIG. 8B. Diffuser surface112 scatters light from the various LED sources, resulting in a widerbeam angle. In general, diffuser surface 112 is preferably configuredwith some combination of differently textured surfaces and/or patterns114, so that light 116 entering the surface will get scattered ordiffused, shown by light 118. For example, lensets that perform thescattering can be rectangular or square shaped domes, and may be smallenough so that the curvature of the lensets is defined by the radius ofthe arcs that create the lensets.

FIG. 9A illustrates a plurality of lunes 120, when viewed from the baseof lens 80 along plane 9-9 of FIG. 8A. Peering into the cylindricalopening, a series of substantially flat or planar lunes 120 extend alongsidewall surface 102 spaced equal distance from central axis 122. Shownare eight lunes, and preferably, the improved lens design hereof usesbetween eight to no more than 20 lunes to enhance color mixing in theinner cylindrical opening into which the LED output enters. Each lunehas an elongated surface that extends the entire length of the sidewallsurface from the planar base on which LEDs 100 reside to upper planarsurface 104. The elongated surface of lunes 120 extend perpendicularfrom the base plane, spaced equal distance along central axis 122 toupper plane 104 that is parallel to the base plane. The lunes are simplyplanar cutouts from lens 80, formed as part of the injection moldingprocess when the fill material is applied to the mold, with the moldouter regions within the cylindrical opening of the lens having aplurality of circumferentially configured planar surfaces.

FIG. 9B is an expanded view of a region showing two lunes 120 a/120 b,and provides a general description as to why such surfaces are definedas lunes. The lune surfaces are formed as a concave-convex area, shownin cross hatch, bounded by two circular arcs. The lune surfaces 120a/120 b are formed therefrom.

It will be appreciated to those skilled in the art having the benefit ofthis disclosure that this invention is believed to provide an improvedlens configuration that achieves improved color mixing. The improvedcolor mixing occurs by treating a collimated outer radial region of theLED module output, while maintaining non-collimation on an inner radialregion fo the LED output. More than three light interactions are neededto achieve the improved color mixing, with both improved spatial andangular uniformity. Further modifications and alternative embodiments ofvarious aspects of the invention will be apparent to those skilled inthe art in view of this description. It is intended that the followingclaims be interpreted to embrace all such modifications and changes.Accordingly, the specification and drawings are to be regarded in anillustrative, rather than a restrictive, sense.

What is claimed is:
 1. A lens for receiving light from at least oneemitter, comprising: a concave light entrance surface that extends intothe lens from a light entry region the concave light entrance surface toreceive the entire emission of at least one emitter, the concave lightentrance surface symmetric about a central axis; wherein at least aportion of the concave light entrance surface includes one or morelunes, each of which is planar and having a length and width, whereinthe length of each lune is greater than the width; a light exit surfaceextending across a light exit region of the lens; and a total internalreflective (TIR) outer surface shaped as a compound parabolicconcentrator (CPC) extending between the light entry region and thelight exit region.
 2. The lens of claim 1 wherein the concave lightentrance surface comprises a cylindrical light entrance surface having asidewall parallel to and equidistant from the central axis and a topsurface.
 3. The lens of claim 2 wherein the top surface of thecylindrical light entrance surface comprises a planar upper surface. 4.The lens of claim 2 wherein the top surface of the cylindrical lightentrance surface comprises a convex upper surface.
 5. The lens of claim2 wherein the one or more lunes comprise a plurality of lunes disposedevenly across the cylindrical sidewall surface, the length of each ofthe plurality of lunes parallel to the central axis and the width ofeach of the plurality of lunes perpendicular to the central axis.
 6. Thelens of claim 1 wherein the light exit surface comprises a concavespherical light exit surface extending across the entirety of the lightexit region of the lens.
 7. The lens of claim 1 wherein the light existsurface comprises a plurality of lenslets for across at least a portionof the light exit surface.
 8. The lens of claim 1, wherein an entiretyof the light entry region and the light exit region comprise a diffusionsurface.
 9. The lens of claim 1, wherein the lens further comprises aunibody construction of transparent material having a refractive indexgreater than air and wherein the unibody is configured between surfacesformed by the concave light entrance surface, the light exit surface,and the TIR outer surface shaped as a CPC.
 10. The lens of claim 1,wherein the TIR outer surface shaped as a CPC is symmetrical about thecentral axis, and the light exit surface is also symmetrical about thecentral axis.
 11. The lens of claim 10, wherein the TIR outer surfaceshaped as a CPC comprises a radial outer dimension symmetric about thecentral axis at the light exit surface that is less than a radial outerdimension of a parabola rotated about the central axis.
 12. The lens ofclaim 1 wherein the lunes form a concave light entrance surface having apolygonal cross-section with respect to the central axis.
 13. A lens forreceiving light from at least one emitter, comprising: a concave lightentrance surface symmetric about a central axis extending into the lens,the concave light entrance surface to receive a light emission from alight source; a light exit surface symmetric about the central axis; anda total internal reflective (TIR) outer surface shaped as a compoundparabolic concentrator (CPC) extending between the light entry regionand the light exit region; wherein a first portion of the light emissionfrom the light source enters a first portion of the concave lightentrance surface and departs the light exit surface as an uncollimatedlight portion; and wherein a remaining portion of the light emissionfrom the light source enters a second portion of the concave lightentrance surface and departs the light exit region as collimated lightportion that surrounds the uncollimated light portion.
 14. The lens ofclaim 13 wherein at least a portion of the concave light entrancesurface includes one or more lunes, each of which is planar and having alength and width, wherein the length of each lune is greater than thewidth.
 15. The lens of claim 14 wherein the concave light entrancesurface comprises a cylindrical light entrance surface having a sidewallparallel to and equidistant from the central axis and an upper surface.16. The lens of claim 15 wherein the upper surface comprises a planarupper surface.
 17. The lens of claim 15 wherein the upper surfacecomprises a convex upper surface.
 18. The lens of claim 15 wherein theone or more lunes are disposed evenly across the cylindrical sidewallsurface, the length of each of the plurality of lunes parallel to thecentral axis and the width of each of the plurality of lunesperpendicular to the central axis.